membrane proteins

Question 1

Functional evidence of proteins in membrane

Answer 1

Facilitated diffusion e.g. glucose
Ion gradients
specificity of cell responses

Question 2

Biochemical evidence of proteins in membrane

Answer 2

Membrane fractionation and electrophoresis

freeze fracture

Question 3

Freeze fracture

Answer 3

Freeze fracture will allow the plasma membrane to split down the lamella
will get two sides of the phospholipid bilayer
P fracture inner
and the E fracture outer
use low angle shadowing to show if proteins are found in membrane or gaps

Question 4

Mobility of proteins and bilayer free modes of motion

Answer 4

Conformational change
rotational
lateral

Question 5

Three ways which membrane protein movement can be restricted

Answer 5

Aggregates of proteins
tethering- either to something outside the cell or the cytoskeleton inside the cell
interaction with other cells

Question 6

How do membrane protein associate with the bilayer

Answer 6

Peripheral

integral

Question 7

Peripheral membrane proteins

Answer 7

Bound to surface
electrostatic and hydrogen bond interactions
removed by changes in pH or in ionic strength

Question 8

Integral

Answer 8

Interact with hydrophobic domains of the lipid bilayer
cannot be removed by manipulation of pH and ionic strength
are removed by agents that compete for nonpolar interactions such as detergents and organic solvents

Question 9

Transmembrane polypeptide characteristics

Answer 9

Amino acids are small, hydrophobic, polar, uncharged

transmembrane domains are alpha helical

Question 10

What does a hydropathy plot show

Answer 10

Will tell you how hydrophilic hydrophobic certain residue of amino acids in your protein is hence can give you an idea if that domain of the protein will be an integral or peripheral

Question 11

What end of protein is normally found in the cytosol

Answer 11

The N terminus

Question 12

Your foresight cytoskeleton

Answer 12

Spectra in has alpha and beta units
binds to transmembrane protein anchors
spectrum lattice adhered through attachment proteins

Question 13

Haemolytic anaemias is caused by what

Answer 13

Issues with the cytoskeleton

Question 14

Hereditary spherocytosis

Answer 14

Spectrum depletion by 40 to 50%
erythrocytes round
more likely to lysis
cleared by spleen

Question 15

Hereditary elliptocytosis

Answer 15

Defect in spectrin molecule
unable to form heterotramers
rugby ball -shaped

Question 16

Role of signal recognition particle

Answer 16

Binds to the signal sequence which is the first 20 hydrophobic amino acids

Question 17

Docking protein

Answer 17

Bind to the signal recognition particle which is bound to the hydrophobic signal sequence, pulling the complex down to the membrane

Question 18

Protein translocated called

Answer 18

sec61

Question 19

How do you get N terminus in cytoplasm

Answer 19

Signal sequence is cleaved off